Twist-drill-grinding jig.



W. E. GROWTHER.

TWIST DRILL GRINDING JIG.

APPLIOATIONKPILED NOV. 18, i909.

978,851 Pate nted 960 20, 1910.

. of the jig.

WILLIAM EDWARD CROWTHER, OF NEW BRIGHTON, ENGLAND.

TWIST-DRILL-GRINDING J IG.

Specification of Letters Patent. Patented Dec. 20, 1910.

Application filed November 18, 1909. Serial No; 528,818.

To all whom it may concern:

Be it known that I, WVILLIAM EDWARD Cnowrrrnn, a subject of GreatBritain, and resident of 1 Shiel road, New Brighton, in the county ofChester, England, engineer, have invented certain new and usefulImprovements in Twist-Drill-Grinding Jigs, for which I have applied forLetters Patent in England, No. 24,904, dated November 19, 1908, and ofwhich the following is a specification.

My invention relates to improvements in twist drill grinding jigswhereby such drills are more easily, expeditiously and accuratelyground. I attain these objects by the mechanism illustrated on theaccompanying drawings in which Figure 1 is a general view of the jigcomplete. Fig. 2 is a side elevation of portion Fig. 3 is a partelevation and part section showing the part shown in Fig. 2 in anotherposition.

Similar letters refer to similar parts on the several views.

This jig for holding a drill while grinding against an emery wheel orgrindstone, is formed of three main portions as shown by the generalview Fig. 1 viz :the base A,

the bracket B and the trough C with the extensions and accessories. Thebase 'A is so made that it can be adjust-ably bolted down to thepedestal or bench of an emery wheel, or it may be otherwise used acrossa lathe bed when an emery wheel is run in a chuck. To allow of adaptingthe position of the bracket B the base A has four fitting faces a, a aand at against any one of which the bracket B can be bolted. Additionaladaptability is secured by the arrangement for swinging the bracketsidewise and clamping it at any angle against the face.

The trough C is of the usual V section and is fitted with a rotaryspindle D and a grooved extension rod E carrying a sliding support F andadjustable back set G. These parts F and G are clamped by screws 7" and9 taking into the groove 6 in the extension rod E. The upper end of thespindle D rests in V bearings cl formed on the upper end of the bracketB and its lower end is socketed upon the upper end of the feed screw Hso that the spindle and trough can be readily lifted from the bracket.The back set G is capable of taking an alternative position as shown inFig. 3 rendering it suitable for use for very short and small drills byturning the part marked J over into the trough 0.

To secure the drill steadily in its position in the trough C whilegrinding a clamp is used consisting of an arch bridge K which slides onthe parallel edges of the trough C. A- screw L passes centrally throughthe bridge K and bears upon the drill. The lower end of the screw isprovided with a short. axial pin or point Z. The right hand side of thetrough C is cut away obliquely at the upper end to permit of the swingwhen grinding. hen setting a drill for grinding the point should beadvanced about two diameters beyond the end of the trough C; aftergrinding the first edge, the drill must be turned over in the trough anexact half turn. In case of drills of large diameter the clamping screwL is adjusted with its axial pin Z against one helical edge of the drillwhile the surrounding fiat surface bears upon the edge and secures it.After the first edge has been ground, the screw L is raised and thedrill turned over until the corresponding helical edge can be secured inthe same manner as the first.

Having now described my invention I deolare that what I claim is 1. Thecombination in a twist drill grinding jig a base in the form of aclamping fork with a lug at one end, to any side of which is locked, atany desired angle, an inclined bracket provided with bearings, and

an adjusting or feeding screw,supporting a spindle secured to the drillrest, said rest being fitted with a sliding bridge provided with ascrew, the point of which bears upon the drill and also with a back setadapted to be used in two positions, substantially as described.

2. In a twist drill grinding jig, a base with a multilateral support atone end thereof, an inclined bracket, provided with bearings, secured toany selected side of the support, a feeding screw adjustable through oneof the said bearings, a drill rest, a spindle secured to the drill restand supported by the feeding screw, and the other of said bearings, asliding bridge, and a back set, on the drill rest.

3. In a twist drill grinding jig, a base in the form of a clamping forkhaving at one end a multilateral support, an inclined bracket, providedwith bearings, secured to any selected side of the support, a drillrest, a spindle secured to the drill rest and supported in one of saidbearings, :1 feeding In Witness whereof I have hereunto set screw aduStable through the other of send my hand 1n the presence of twowltnesses.

bearin 's and engaging with said spindle, a sliding bridge mounted uponthe drill rest WILLIAM EDWARD CROWTHER' provided with a setscrew havinga pin point Vitnesses:

and aback set for the drill rest to be used H. WATSON, in two positions.H. WILLIAMS.

